This invention relates generally to an improved apparatus and method for purifying contaminated industrial oil and, more particularly, such apparatus and method which are easily adapted to an individual user's purification requirements.
Oil is used extensively as a lubricant to protect the moving parts of machinery from the effects of friction. As oil is used, a variety of contaminants act to undermine the oil's protection capabilities. These impurities include: acidic compounds, oxidation by-products, metallic soaps, colloidal carbons and water. Removal of these impurities improves the lubricating performance and non-corrosive characteristics of the oil, thereby reducing equipment wear and replacement costs. Once purified, the life of the oil can be extended indefinitely.
There are numerous conventional methods for the purification of contaminated lubrication oil as well as the equipment developed to practice this method. Various cleansing techniques, including filtration, adsorption, coagulation and centrifuging, have been used separately and in combination.
In general, different methods of passing a contaminated fluid through porous media to effect mechanical filtration have also been conventionally used. Several references incorporate passing contaminated fluids through layers of particulate filter media to trap impurities. Typical references to this method are U.S. Pat. No. 4,197,205 of Hirs; U.S. Pat. No. 1,838,263 of Helley and U.S. Pat. No. 3,202,286 of Smit. Each of these patents proposes layering the filter media so that the size of the particles decreases in the direction of flow in order to trap increasingly smaller impurities.
Centrifugation, like filtration, is a physical operation sometimes used in fluid purification. Both U.S. Pat. No. 3,954,611 by Reedy and U.S. Pat. No. 4,498,992 by Garrett use centrifuges to remove solids, sludges and water from contaminated oil.
The above-noted Garrett patent also proposes contacting contaminated oil with impurity adsorbent material to remove contaminants from the oil and, in particular, using a singular adsorbent (Fuller's earth) in the purification process. The use of an individual adsorbent in a purification process has had limited success since a single adsorbent limits the adsorption of impurties to those contaminants which readily adhere to that particular adsorbent's surface. In addition, contaminated oil most often contains a number of impurities that need to be removed and that are not adapted to be removed by a single adsorbent. In addition, in the presence of several contaminants which are individually attracted to an adsorbent, a particular impurity may be more readily adsorbed to the exclusion of others. Therefore, in a mono-adsorbent system, preferential adsorption allows some impurities to avoid removal.
Regardless of what purification techniques are used, present oil purification systems are not readily adaptable to a particular user's needs. The contamination profile (type and concentration of impurities present) of lubrication oil is dependent upon the equipment and operating conditions of the system it protects. This profile not only changes from system to system, but may vary within a particular system as operating conditions fluctuate. The existing purification processes are unable to adapt to these variations. Therefore, these processes cannot ensure a user's purification requirement is achieved independent of the system, nor can they ensure a protection as the system's contamination profile changes.